Final answer:
Water penetration can cause moisture damage, mold growth, and structural deterioration in a cavity wall. Proper construction techniques and waterproofing measures are necessary to prevent water penetration and maintain the integrity of the wall.
Step-by-step explanation:
When water penetrates the outer wythe of a cavity wall, it can cause various effects depending on the materials and design of the wall. If the outer wythe is highly permeable, water can seep through the wall and saturate the insulation or structural elements, leading to moisture damage, mold growth, and structural deterioration. In some cases, the water may evaporate from the interior surface of the wall, causing efflorescence, which is the deposit of salts and minerals left behind as the water evaporates.
To prevent water penetration, cavity walls are typically constructed with a drainage system and waterproofing materials. This can include a layer of waterproof membrane or a vapor barrier applied to the outer wythe, weep holes or vents near the base of the wall to allow water to drain out, and proper flashings and sealants to prevent water entry at joints and openings.
In summary, when water penetrates the outer wythe of a cavity wall, it can lead to moisture damage, mold growth, and structural deterioration. Proper construction techniques, including the use of waterproofing materials and drainage systems, are essential to prevent water penetration and maintain the integrity of the cavity wall.